U.S. patent application number 12/757120 was filed with the patent office on 2010-10-14 for starter having noise reduction structure.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Kiyokazu Haruno, Mitsuhiro Murata, Masami NIIMI.
Application Number | 20100257975 12/757120 |
Document ID | / |
Family ID | 42813043 |
Filed Date | 2010-10-14 |
United States Patent
Application |
20100257975 |
Kind Code |
A1 |
NIIMI; Masami ; et
al. |
October 14, 2010 |
STARTER HAVING NOISE REDUCTION STRUCTURE
Abstract
The present invention provides a starter, including a motor
generating torque; a shaft rotating by the torque; a clutch fitting
an outer periphery of the shaft; a pinion gear receiving the
torque; a pinion control means configured to allow the pinion gear
integrally with the clutch to be pushed out; a motor control means
for controlling current supplied to the motor; and an inner tube
that is arranged to be extended from the inner and in the direction
opposite to the motor, supports the pinion gear so as to inhibit
rotation thereof with respect to the periphery of the inner tube,
and supports the pinion gear to be slidable; wherein a gear-side
face and a tube-side face are formed in the pinion gear and the
inner tube, respectively, in which the faces are facing each other,
and a cushioning member is disposed between the gear-side face and
the tube-side face.
Inventors: |
NIIMI; Masami; (Handa-shi,
JP) ; Murata; Mitsuhiro; (Niwa-gun, JP) ;
Haruno; Kiyokazu; (Anjo-shi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
42813043 |
Appl. No.: |
12/757120 |
Filed: |
April 9, 2010 |
Current U.S.
Class: |
74/7C |
Current CPC
Class: |
F02N 15/067 20130101;
Y10T 74/134 20150115; Y10T 74/131 20150115; F02N 11/087 20130101;
F02N 11/0855 20130101; F02N 15/063 20130101 |
Class at
Publication: |
74/7.C |
International
Class: |
F02N 15/02 20060101
F02N015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 10, 2009 |
JP |
2009-096104 |
Claims
1. A starter mounted on a vehicle for starting the engine,
comprising: a motor that generates torque by being energized; an
output shaft that rotates by receiving the torque from the motor; a
clutch that fits an outer periphery of the output shaft; a pinion
gear that receives the torque generated by the motor via the
clutch; a pinion control means configured to allow the pinion gear
integrally with the clutch to be pushed out in the axial direction;
a motor control means for controlling current supplied to the motor
on and off; and an inner tube that is arranged to be cylindrically
extended from the inner and in the direction opposite to the motor,
supports the pinion gear so as to inhibit rotation thereof with
respect to the periphery of the inner tube, and supports the pinion
gear to be slidable in the axial direction; wherein a gear-side
pressure receiving face and a tube-side pressure receiving face are
formed in the pinion gear and the inner tube, respectively, in
which the both faces are facing each other with a predetermined
distance in the axial direction, and a cushioning member is
disposed between the gear-side pressure receiving face and the
tube-side pressure receiving face.
2. The starter according to claim 1, wherein the cushioning member
is an elastic member made of rubber or elastomer which is a
composite of rubber and resin.
3. The starter according to claim 1, wherein the cushioning member
is a helical compression spring.
4. The starter according to claim 1, wherein the cushioning member
is an elastic member that combines a helical compression spring and
a rubber.
5. The starter according to claim 1, wherein the cushioning member
is elastic member that combines a helical compression spring and
elastomer which is a composite of rubber and resin.
6. The starter according to claim 1, wherein a pinion stopper is
disposed at an end portion of the inner tube positioned opposite to
the tube in order to restrict the movement of the pinion gear in
the direction opposite to the clutch, an initial load is applied to
the cushioning member to prevent the pinion gear from moving in the
direction opposite to the pinion stopper due to vibration
acceleration effected to the starter from the outside thereof.
7. The starter according to claim 1, wherein an expansion
preventing means is provided at the outer periphery side of the
cushioning member to prevent the cushioning member from radially
expanding to the outside by rotational force of the pinion gear
integrally with the clutch.
8. The starter according to claim 1, wherein the maximum diameters
of the gear-side pressure receiving face and the tube-side pressure
receiving face are smaller than the root diameter of the pinion
gear, and the minimum diameters of the gear-side pressure receiving
face and the tube-side pressure receiving face are larger than the
outer diameter of the inner tube.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and claims the benefit of
priority from earlier Japanese Patent Application No. 2009-96104
filed Apr. 10, 2009, the description of which is incorporated
herein by reference,
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field of the Invention
[0003] The present invention relates to a starter for starting an
engine and, more particularly, the present invention relates to a
starter having a structure that reduces operation noise
thereof.
[0004] 2. Related Art
[0005] Conventionally, automatic engine stop/restart systems
(hereinafter referred to as "idle stop system(s)") are known. Such
an idle stop system is able to automatically control stop/restart
of an engine.
[0006] Specifically, Japanese patent Laid-open Publication No.
2005-330813 discloses an idle stop system. The idle stop system
includes a pinion control means for controlling the pinion gear to
be pushed out towards a ring gear and a motor control means for
controlling current to be supplied to the motor on/off. In the idle
stop system, the pinion control means and the motor control means
are configured such that the both means can be operated
individually. With this configuration, even if an event requiring
an engine-restart occurs during the engine rotation is decreasing
until the engine completely stopped, the pinion gear is pushed out
to the ring gear while being rotated whereby the pinion gear meshes
with the ring gear. As a result, the engine-restart can be made by
powering the motor after completion of the meshing, With this
method applied to this configuration, compared to the
engine-restart being made after the complete engine stop, the
driver of the vehicle does not feel anything uncomfortable because
of the smooth engine-restart.
[0007] According to the above-described prior art, even if the
engine-restart request is not issued while the engine rotation is
decreasing, the pinion gear can be meshed with the ring gear when
the rotation speed of the ring gear reaches a predetermined value.
Subsequently, the meshing between pinion gear and the ring gear can
be maintained until the complete engine stop without powering the
motor. Therefore, since the pinion gear and the ring gear remain
meshed when next engine-restart request occurs, necessary period
for the engine-restart can be reduced.
[0008] An increase in vehicles including an idle-stop system that
automatically controls stop and restart of the engine is expected
in the next few years. As the vehicles including the idle stop
system increase, for instance, it is expected situations that
vehicles become stuck in a local road due to a traffic jam. In this
case, it is considered that the engines in the vehicles start at
almost the same time. As a result, operation noise of the starter
when the engine starts increases and such a noise may cause a noise
pollution problem along the road side.
[0009] The dominant noise elements accounting for the operation
noise of the starter includes a strike noise that occurs when the
end face of the pinion gear strikes the end face of the ring gear,
a strike noise caused by the teeth faces of the pinion gear and the
ring gear when the pinion gear meshes with the ring gear, and an
operation noise of the electromagnetic solenoid which is a part of
the pinion control means (i.e., a strike noise that occurs when a
plunger strikes a core).
[0010] However, as described above, when the pinion gear meshes
with the ring gear while the engine rotation is decreasing without
supplying power to the motor, the end face of the pinion gear
strikes the end face of the ring gear and at almost the same time,
the plunger of the electromagnetic solenoid strikes the core. As a
result, two types of noises caused by both striking influence each
other and generate an impact noise that accumulates the noises.
Moreover, at the moment, since the motor is not powered so that no
operation sound is generated by the motor. Hence, the
above-described impact noise significantly stands out and makes the
driver of the vehicle uncomfortable.
SUMMARY OF THE INVENTION
[0011] The present invention has been made in consideration of the
foregoing conventional situation, and an object of the present
invention is to provide a starter in which an impact shock caused
by striking between the pinion gear and the ring gear is reduced
whereby noise caused by the impact shock when the engine starts can
be reduced.
[0012] In order to achieve the object, the present invention
provides, as one aspect, a starter mounted on a vehicle for
starting the engine, including: a motor that generates torque by
being energized; an output shaft that rotates by receiving the
torque from the motor; a clutch that fits an outer periphery of the
output shaft; a pinion gear that receives the torque generated by
the motor via the clutch; a pinion control means configured to
allow the pinion gear integrally with the clutch to be pushed out
in the axial direction; a motor control means for controlling
current supplied to the motor on and off; and an inner tube that is
arranged to be cylindrically extended from the inner and in the
direction opposite to the motor, supports the pinion gear so as to
inhibit rotation thereof with respect to the periphery of the inner
tube, and supports the pinion gear to be slidable in the axial
direction; wherein a gear-side pressure receiving face and a
tube-side pressure receiving face are formed in the pinion gear and
the inner tube, respectively, in which the both faces are facing
each other with a predetermined distance in the axial direction,
and a cushioning member is disposed between the gear-side pressure
receiving face and the tube-side pressure receiving face.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In the accompanying drawings:
[0014] FIG. 1 is a general view of a starter according to a first
embodiment of the present invention;
[0015] FIG. 2 is a sectional view of a pinion movable body
according to the first embodiment;
[0016] FIG. 3 is a sectional view of a solenoid for pushing out a
pinion and a solenoid for supplying current to a motor;
[0017] FIG. 4 is an electric circuit diagram of the starter;
[0018] FIG. 5A is a graph of sound pressure which is produced at
the time the starter operates;
[0019] FIG. 5B is a graph of engine speed;
[0020] FIG. 5C is a graph of starter current;
[0021] FIG. 6 shows results of the measurement of sound pressure
obtained while pinion preset is performed;
[0022] FIG. 7 is a sectional view of a pinion movable body
according to a second embodiment;
[0023] FIG. 8 is a sectional view of a pinion movable body
according to a third embodiment; and
[0024] FIG. 9 is a sectional view of a pinion movable body
according to a fourth embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] Hereinafter, embodiments of the present invention will now
be described in connection with the accompanying drawings.
[0026] (First Embodiment)
[0027] A starter 1 according to a first embodiment is applied to an
idle stop system which automatically controls stop/restart of an
engine.
[0028] As shown in FIG. 1, the starter 1 includes a motor 2, an
output shaft 3, a pinion movable body (described later). The motor
2 generates torque. The output shaft 3 is rotated by the motor 2.
The pinion movable body is provided so as to be movable on the
periphery of the output shaft 3 and in the axial direction thereof.
The starter 1 further includes a solenoid 5 (hereinafter referred
to as "pinion solenoid 5") which pushes out the pinion movable body
in the direction opposite to the motor (leftward in FIG. 1) via a
shift lever 4, a solenoid 6 (hereinafter referred to as "motor
solenoid 6") which opens/closes a motor contact (described later),
and the like. A reduction gear (e.g. planetary gear reducer) may be
provided between an armature 2a of the motor 2 (see FIG. 4) and the
output shaft 3 so that the torque of the armature 2a is reduced and
transmitted to the output shaft 3.
[0029] The pinion movable body is configured with a clutch 7 and a
pinion gear 8 as described below.
[0030] The clutch 7 includes a spline barrel 7a, an outer 7b, an
inner 7c, a roller 7d, and the like. The spline barrel 7a fits the
periphery of the output shaft 3 (helical spline fitting). The outer
7b is provided integrally with the spline barrel 7a. The inner 7c
is arranged at the inner side of the outer 7b so as to be rotatable
with respect to the outer 7b. The roller 7d interrupts the
transmission of the torque between the outer 7b and the inner 7c.
That is, the pinion movable body acts as a known one-direction
clutch, which transmits torque in only one direction from the outer
7b to the inner 7c.
[0031] The clutch 7 has an inner tube 9 provided integrally with
the inner 7c. The inner tube 9 fits the periphery of the output
shaft 3 via bearings 10 so as to be rotatable with respect to the
output shaft 3.
[0032] As shown in FIG. 2, the inner tube 9 cylindrically extends
from the inner 7c and in the direction opposite to the motor
(leftward in FIG. 2). A straight spline 9a is formed on the
periphery of the inner tube 9 and in the axial direction thereof. A
flange 9b is provided at the inner side end portion of the inner
tube 9. The outer diameter of the flange 9b is larger than that of
the straight spline 9a. The end face of the flange 9b, which is
located at a position opposite to the inner in the axial direction
of the flange 9b (left side in FIG. 2), serves as a tube-side
pressure receiving face 9c.
[0033] A pinion gear 8 has a hale which fits the periphery of the
inner tube 9 (hereinafter, referred to as "fitting hole"). A
straight spline 8a (see FIG. 2) is formed on the inner periphery of
the fitting hole. The straight spline 8a engages with the straight
spline 9a of the inner tube 9 and rotates integrally with the inner
tube 9. The straight spline 8a is movable on the periphery of the
inner tube 9 and in the axial direction thereof. As shown in FIG.
2, the movement of the pinion gear 8 in the direction opposite to
the clutch is restricted by a pinion stopper 11 disposed at an end
portion of the inner tube 9 positioned opposite to the inner
side.
[0034] A large-diameter hole is formed at the inner side of the
pinion gear 8. The inner diameter of the large-diameter hole is
larger than that of the fitting hole in which the straight spline
8a is formed. As shown in FIG. 2, the large-diameter hole is formed
at the clutch side with respect to the fitting hole (right side in
FIG. 2) in the axial direction of the pinion gear 8. A step is
provided between the fitting hole and the large-diameter hole. The
step serves as a gear-side pressure receiving face 8b which faces
the tube-side pressure receiving face 9c with a predetermined
distance in the axial direction of the inner tube 9. The inner
diameter of the large-diameter hale is determined so that the
pinion gear 8 can slide on the periphery of the flange 9b of the
inner tube 9. The length of the pinion gear 8 in the axial
direction thereof is slightly longer than the distance between the
pinion-side end face of the pinion stopper 11 and the tube-side
pressure receiving face 9c in the axial direction. That is, as
shown in FIG. 2, the pinion gear 8 is located so that the rear end
thereof is positioned so as to be slightly distanced from the
tube-side pressure receiving face 9c to the clutch side in the
axial direction when the front end thereof contacts the pinion-side
end face of the pinion stopper 11.
[0035] A cushioning member 12 is arranged on the inner side of the
large-diameter hole formed in the pinion gear 8. The cushioning
member 12 is an elastic member made of rubber or elastomer which is
a composite of rubber and resin. The cushioning member 12 is held
between the tube-side pressure receiving face 9c and the gear-side
pressure receiving face 8b in a state where an initial load is
applied therebetween, that is, elastic force is accumulated
therebetween. Due to the initial load applied to the cushioning
member 12, the pinion gear 8 is pressed against the pinion stopper
11. The initial load applied to the cushioning member 12 preferably
has the magnitude which can prevent the pinion gear 8 from moving
in the direction opposite to the pinion stopper due to vibration
acceleration effected to the starter 1 from the outside
thereof.
[0036] Hereinafter, configurations of the pinion solenoid S and the
motor solenoid 6 are described. The pinion solenoid 5 and the motor
solenoid 6 share a fixed core 13. The pinion solenoid 5 and the
motor solenoid 6 are integral with each other in the axial
direction so as to hold the fixed core 13. As shown in FIG. 1, the
pinion solenoid 5 and the motor solenoid 6 are fixed to a starter
housing 14 so as to be parallel to the motor 2.
[0037] As shown in FIG. 3, the pinion solenoid 5 includes a
solenoid case 15, an excitation coil 16, a plunger 17, and a joint
18, in addition to the fixed core 13. The excitation coil 16 is
accommodated in the solenoid case 15. The plunger 17 is movable in
the axial direction in a state where the plunger 17 faces the fixed
core 13. The joint 18 transmits the movement of the plunger 17 to
the shift lever 4.
[0038] As shown in FIG. 4, the excitation coil 16 has one end
portion which is connected to a connector terminal 19 and the other
end portion which is connected to the surface of the fixed core 13,
for example, for grounding by welding or the like. The connector
terminal 19 is connected with an electrical wiring which is
connected to a starter relay 20.
[0039] The starter relay 20 is subjected to on/off control of an
electronic control unit 21 (hereinafter referred to as "ECU 21")
which controls the operation of the starter 1. When the starter
relay 20 is controlled and turned on by the ECU 21, current is
supplied to the excitation coil 16 from a battery 22 via the
starter relay 20.
[0040] When the fixed core 13 is magnetized upon supply of current
to the excitation coil 16, the plunger 17 is attracted to the fixed
core 13 against the reaction force of a return spring 23 arranged
between the plunger 17 and the fixed core 13. The plunger 17 has a
substantially cylindrical shape with a cylindrical bore axially
formed in the radial center thereof. The cylindrical bore is formed
in the plunger 17 so that the plunger 17 is opened at one axial end
side (leftward end side in FIG. 3) thereof and bottomed at the
other axial end side.
[0041] The rod-shaped joint 18 is inserted into the cylindrical
bore of the plunger 17 together with a drive spring 24. The joint
18 has one end in which an engagement groove 18a is formed which
engages with one end of the shift lever 4, and the other end at
which a flange 18b is formed. The one end of the joint 18 projects
from the cylindrical bore of the plunger 17. The flange 18b has an
outer diameter corresponding to the inner diameter of the
cylindrical bore so that the flange 18b can slidably move along the
inner periphery of the cylindrical bore. Being loaded by the drive
spring 24, the flange 18b is pressed against the bottom face of the
cylindrical bore. With the movement of the plunger 17, the pinion
gear 8 is pushed out in a direction opposite to the motor via the
shift lever 4. As a result, an end face of the pinion gear 8 comes
into contact with an end face of a ring gear 25. During the
movement of the plunger 17 from this instance up until the plunger
17 is attracted to the fixed core 13, the drive spring 24 is
compressed arid stores reaction force for allowing the pinion gear
8 to engage with the ring gear 25 of the engine.
[0042] As shown in FIG. 3, the motor solenoid 6 includes a
cylindrical yoke 26, a excitation coil 27, a plunger 28, a contact
cover 29, two terminal bolts 30, 31, a pair of fixed contacts 32,
and a movable contact 33, in addition to the fixed core 13. The
yoke 26 is integrally with the solenoid case 15 by extending the
portion of the yoke 26 positioned at the opening side of the
solenoid case 15 in the axial direction. The excitation coil 27 is
arranged inside the yoke 26. The plunger 28 is movable in the axial
direction in a state where the plunger 28 faces the fixed core 13.
The contact cover 29 is made of resin and attached to yoke 26 so
that the contact cover 29 closes the opening of the yoke 26. The
two terminal bolts 30 and 31 are fixed to the contact cover 29. The
pair of fixed contacts 32 is connected to a motor circuit via the
respective two terminal bolts 30 and 31. The movable contact 33
establishes electrical connection between the pair of fixed
contacts 32.
[0043] As shown in FIG. 4, the excitation coil 27 has one end which
is connected to an external terminal 34 and the other end which is
connected to the surface of the fixed core 13, for example, by
welding or the like for grounding. The external terminal 34
projects outward from the end face of the contact cover 29 while
being connected with an electrical wiring which is connected to the
ECU 21.
[0044] A magnetic plate 35 is arranged at a position opposite to
the fixed core side of the excitation coil 27. The magnetic plate
35 has an annular shape and forms a part of a magnetic circuit. The
outer peripheral end face of the magnetic plate 35 positioned at
the coil side (left side in FIG. 3) comes into contact with a step
provided at the inner periphery of the yoke 26, thereby restricting
the position of the magnetic plate 35 at the coil side.
[0045] When the fixed core 13 is magnetized upon supply of current
to the excitation coil 27, the plunger 28 is attracted to the fixed
core 13 against the reaction force of a return spring 36 arranged
between the plunger 28 and the fixed core 13.
[0046] The contact cover 29 has a cylindrical leg portion 29a. The
contact cover 29 is arranged in a state where the leg portion 29a
is inserted into the yoke 26 so that an end face of the leg portion
29a is brought into contact with the surface of the magnetic plate
35, Thus, the contact cover 29 is caulked and fixed to the yoke 26.
Of the two terminal bolts 30 and 31, the terminal bolt 30 is a B
terminal bolt to which a battery cable 37 (see FIG. 4) is
connected, and the terminal bolt 31 is an M terminal bolt to which
a motor lead wire 38 (see Fig, 1) is connected.
[0047] The pair of fixed contacts 32 is provided separately from
the two terminal bolts 30 and 31, for example, and is fixed to the
two terminal bolts 30 and 31 inside the contact cover 29.
[0048] The movable contact 33 is provided on the side opposite to
the plunger 28 (right side in FIG. 3) and is located at a position
more distanced from the plunger 28 than at the position where the
pair of fixed contacts 32 is located. The movable contact 33 is
pressed against an end face of a resinous rod 39 fixed to the
plunger 28 while being loaded by a contact pressure spring 40. In
this regard, the initial load of the return spring 36 is set to a
value larger than that of the initial load of the contact pressure
spring 40. Therefore, when current is not supplied to the
excitation coil 27, the movable contact 33 is allowed to sit on an
inner seat surface of the contact cover 29 in a state of pressing
and contracting the contact pressure spring 40.
[0049] The motor contact mentioned hereinbefore is formed of the
pair of fixed contacts 32 and the movable contact 33. When the
movable contact 33 comes into contact with the pair of fixed
contacts 32 and is biased by the contact pressure spring 40,
current is applied across the fixed contacts 32, whereby the motor
contact is closed. On the other hand, when the movable contact 33
comes out of contact with the pair of fixed contacts 32, the
current application across the contacts 32 is shut off, whereby the
motor contact is opened.
[0050] Next, an operation of the starter 1 is described.
[0051] a) In a case where the engine is started in a normal manner
(that is, a case where the engine is started by the user's turn-on
operation of an ignition switch (not shown) in a state where the
engine is completely stopped):
[0052] The ECU 21 effects control to close the starter relay 20
upon reception of an engine start signal produced by the user's
turn-on operation of the ignition switch. Thereby, the excitation
coil 16 of the pinion solenoid 5 is supplied with current from the
battery 22, whereby the plunger 17 is moved by being attracted to
the magnetized fixed core 13. With the movement of the plunger 17,
the pinion gear 8 is pushed out integrally with the clutch 7 in the
direction opposite to the motor via the shift lever 4 and stops in
a state where the end face of the pinion gear 8 is in contact with
the end face of the ring gear 25.
[0053] After expiration of the predetermined time following the
production of the engine start signal, the ECU 21 outputs a turn-on
signal to the excitation coil 27 of the motor solenoid 6. Thereby,
current is supplied to the excitation coil 27, whereby the plunger
28 is attracted to the fixed core 13. Thereby, the movable contact
33 comes into contact with the pair of fixed contacts 32 and is
biased by the contact pressure spring 40, whereby the main contact
is closed. As a result, current is supplied to the motor 2 to
generate torque of the armature 2a. The torque is then transmitted
to the output shaft 3. Furthermore, the rotation of the output
shaft 3 is transmitted to the pinion gear 8 via the clutch 7. When
the pinion gear 8 has rotated up to a position enabling engagement
with the ring gear 25, the pinion gear 8 engages with the ring gear
25 by the reaction force stored in the drive spring 24. Thereby,
the torque is transmitted from the pinion gear 8 to the ring gear
25 to crank the engine.
[0054] When the engine starts, the ECU 21 outputs a turn-off
signal, which stops the supply of current to the excitation coil 16
of the pinion solenoid 5 and the excitation coil 27 of the motor
solenoid 6. As a result, the attraction force of the pinion
solenoid 5 is lost, whereby the plunger 17 is pushed back. Thereby,
the pinion gear 8 is released from the ring gear 25. Then, the
pinion gear 8 moves on the periphery of the output shaft 3 to the
rest position (shown in FIG. 1) integrally with the clutch 7 and
stops. In addition, the attraction force of the motor solenoid 6 is
lost, whereby the plunger 28 is pushed back. Thereby, the motor
contact is opened to stop the power feed from the battery 22 to the
motor 2. Then, the rotation of the armature 2a gradually
decelerates and stops.
[0055] b) In a case where an idle stop is performed when the
vehicle is in an idling state or a case where a user operates an
ignition switch to the engine stop position:
[0056] The ECU 21 outputs an engine stop signal to stop the fuel
injection and the supply of intake air to the engine. Thereby, the
engine proceeds to a stop process in which, as shown in FIG. 5B,
the rotation of the ring gear 25 (shown as engine speed in FIG. 5B)
starts to decelerate. When the rotation of the ring gear 25
decelerates up to the predetermined engine speed, the ECU 21
outputs a turn-on signal to the excitation coil 16 of the pinion
solenoid 5. As a result, the pinion gear 8 is pushed out integrally
with the clutch 7 in the direction opposite to the motor. Thereby,
the end face of the pinion gear 8 comes into contact with the end
face of the ring gear 25. Thereafter, when the ring gear 25 rotates
up to the position at which the ring gear 25 can engage with the
pinion gear 8, the engagement between the pinion gear 8 and the
ring gear 25 is established.
[0057] Thereafter, the ring gear 25 continues to rotate with
deceleration and stops. The pinion gear 8 rotates together with the
ring gear 25 while engaging with the ring gear 25, and stops. In
the meantime, as shown in FIG. 5C, the excitation coil 16 of the
pinion solenoid 5 is supplied with holding current by which the
engagement between the pinion gear 8 and the ring gear 25 can be
maintained. Hereinafter, the following operation is referred to as
"pinion preset", which is performed in the stop process of the
engine. In this operation, the pinion solenoid 5 is actuated during
rotation of the ring gear 25 to make the pinion gear 8 engage with
the ring gear 25. While the pinion preset is performed, current is
not supplied to the excitation coil 27 of the motor solenoid 6.
[0058] c) When the engine is restarted after the pinion preset:
[0059] Next, when the ECU 21 outputs a restart signal for the
engine, current is supplied to the excitation coil 27 of the motor
solenoid 6, whereby the motor contact is dosed. As a result,
current is supplied to the motor 2 to generate torque of the
armature 2a. At this time, since the pinion gear 8 has already
engaged with the ring gear 25, the torque of the motor 2. is
transmitted from the pinion gear 8 to the ring gear 25 to crank the
engine.
[0060] (Advantages of the First Embodiment)
[0061] In the starter 1 of the present embodiment, the pinion
solenoid 5 and the motor solenoid 6 are separately controlled by
the ECU 21. Hence, in a case where the engine is stopped when the
vehicle is in an idling state, even after only the pinion solenoid
5 is actuated to engage the pinion gear 8 with the rotating ring
gear 25 and then the rotating ring gear 25 stops, the engagement
between the pinion gear 8 and the ring gear 25 can be maintained.
Thereafter, when the engine is restarted, the pinion gear 8 has
already engaged with the ring gear 25. Therefore, only actuating
the motor solenoid 6 is required, which closes the motor contact.
That is, when the engine is restarted, the pinion movable body is
not required to be pushed out, which shorten the time to make the
pinion gear 8 engage with the ring gear 25. Therefore, the engine
can restart quickly.
[0062] While the pinion preset is performed, at the substantially
same time when the end face of the pinion gear 8 strikes the end
face of the rotating ring gear 25, the plunger 17 of the pinion
solenoid 5 strikes the fixed core 13. Hence, impact noises due to
the two impacts are produced and combined with each other. When
sound pressure is measured which is produced at the time the
starter 1 operates, as shown in FIG. 5A, the sound pressure level
of the impact noises is larger than that of the operation noise of
the starter 1 produced at the time the engine normally starts. In
addition, when the pinion preset is performed, current is not
supplied to the motor 2. Therefore, noises due to the operation of
the motor 2 are not produced, which emphasizes only the above
impact noises remarkably. FIG. 5A shows a waveform of sound
pressure produced at the time the starter 1 operates. FIG. 5B shows
a waveform of engine speed. FIG. 5C shows a waveform of starter
current. The arrow "A" in FIG. 5A indicates the sound pressure
produced at the time the pinion preset is performed (the time the
pinion gear 8 is engaged with the ring gear 25 by actuating the
pinion solenoid 5 while the rotation of the ring gear 25
decelerates).
[0063] To solve the above problems, in the starter 1 according to
the embodiment, the cushioning member 12 is incorporated into the
pinion movable body. Specifically, the cushioning member 12, which
is an elastic member made of rubber, elastomer, or the like, is
arranged between the tube-side pressure receiving face 9c formed by
the flange 9b of the inner tube 9 and the step provided between the
fitting hole and the large-diameter hole of the pinion gear 8.
Hence, when the end face of the pinion gear 8 strikes the end face
of the ring gear 25, the member 12 is contracted between the
tube-side pressure receiving face 9c and the gear-side pressure
receiving face 8b, which reduces the impact between the end face of
the pinion gear 8 and the end face of the ring gear 25. Therefore,
the noise of the starter 1 can be reduced which is produced due to
the impact propagated to the output shaft 3 and the like.
[0064] FIG. 6 shows results of the measurement of sound pressure at
point "A" shown in FIG. 5A. The measurement is conducted by using
the starter 1 in which the cushioning member 12 is incorporated
into the pinion movable body, and the conventional starter which
does not have the cushioning member 12. In FIG. 5, the axis of
abscissa indicates rotating speed in meshed state between the
pinion gear 8 and the ring gear 25, and the axis of ordinate
indicates sound pressure. As shown in FIG. 6, the starter 1
according to the embodiment can reduce the sound pressure while the
pinion preset is performed, compared with the conventional
starter.
[0065] As described above, the starter 1 according to the
embodiment can reduce the noise (the noise of the starter 1)
produced when the engine is restarted after an idle stop. Hence, an
idle stop system can be provided which is comfortable for a user,
without harming the environment along roads.
[0066] In addition, in the pinion movable body according to the
embodiment, the cushioning member 12 is disposed at the inner
periphery of the large-diameter hole formed in the pinion gear 8.
Hence, an expansion preventing means can be provided at the outer
periphery side of the cushioning member 12. That is, as shown in
FIG. 2, a boss 8c of the pinion gear 8, which forms the
large-diameter hole, is provided at the outer periphery side of the
cushioning member 12. Hence, the boss 8c can functions as the
expansion preventing means, which prevents the cushioning member 12
from radially expanding to the outside by centrifugal force when
the pinion movable body rotates. Thereby, the pinion movable body
is pushed out to the ring gear 25 of the engine. Even when the end
face of the pinion gear 8 strikes the end face of the ring gear 25,
the function of the cushioning member 12 is not degraded which
reduces the impact between the end face of the pinion gear 8 and
the end face of the ring gear 25, thereby exerting the
predetermined effects of the cushioning member 12.
[0067] In addition, in the pinion movable body according to the
embodiment, the maximum diameters of the gear-side pressure
receiving face 8b and the tube-side pressure receiving face 9c are
smaller than the root diameter of the pinion gear 8, and the
minimum diameters of the gear-side pressure receiving face 8b and
the tube-side pressure receiving face 9c are larger than the outer
diameter of the inner tube 9. According to the configuration, a
space for the cushioning member 12 can be provided between the root
diameter of the pinion gear 8 and the outer diameter of the inner
tube 9. Furthermore, the cushioning member 12 can be disposed
within the axial dimension of the pinion gear 8. Hence, the pinion
movable body is prevented from increasing in size, while the
cushioning member 12 can be incorporated into the pinion movable
body.
[0068] (Second Embodiment)
[0069] According to a second embodiment, as shown in FIG. 7, a
helical compression spring 41 is employed as the cushioning member
12. According to the configuration, since a general-purpose helical
compression spring can be used as the helical compression spring
41, manufacturing costs of the starter can be reduced.
[0070] (Third Embodiment)
[0071] According to a third embodiment, as shown in FIG. 8, the in
combination of an elastic body such as rubber or elastomer and the
helical compression spring 41 is used as the cushioning member
12.
[0072] According to the configuration, the impact is absorbed by
the helical compression spring 41 and is reduced by the elastic
body, whereby the noise of the starter can be further reduced.
[0073] (Fourth Embodiment)
[0074] According to a fourth embodiment, axial length of the teeth
of the pinion gear 8 is shortened with respect to that of the boss
8c.
[0075] The axial length of the teeth of the pinion gear 8 is simply
required so that the teeth of the pinion gear S can engage with the
ring gear 25. Hence, as shown in FIG. 9, the axial length of the
teeth can be shortened with respect to that of the boss Sc.
Meanwhile, lengthening the axial length of the boss 8c compared
with that of the teeth can provide the expansion preventing means
for the cushioning member 12 at the periphery of the large-diameter
hole.
[0076] It will be appreciated that the present invention is not
limited to the configurations described above, but any and all
modifications, variations or equivalents, which may occur to those
who are skilled in the art, should be considered to fall within the
scope of the present invention.
* * * * *